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NEET Previous year chemistry questions Hydrocarbons

1. Which of the following alkane cannot be made in good yield by Wurtz reaction?  (NEET 2020)

(a) n-Hexane                              (b) 2, 3-Dimethylbutane

(c) n-Heptane                             (d) n-Butane

2. The alkane that gives only one monochloro product on chlorination with Cl2 in presence of diffused sunlight is                                (NEET 2019)

(a) 2,2-dimethylbutane              (b) neopentane

(c) n-pentane                             (d) isopentane.

3. Hydrocarbon (A) reacts with bromine by substitution to form an alkyl bromide which by Wurtz reaction is converted to gaseous hydrocarbon containing less than four carbon atoms. (A) is                   (NEET 2018)

(a) CH ≡ CH                              (b) CH2 = CH2

(c) CH3 — CH3                          (d) CH4

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4. With respect to the conformers of ethane, which of the following statements is true?  (NEET 2017)

(a) Bond angle changes but bond length remains same.

(b) Both bond angle and bond length change.

(c) Both bond angle and bond length remain same.

(d) Bond angle remains same but bond length changes.

5. The correct statement regarding the comparison of staggered and eclipsed conformations of ethane, is    (NEET-I 2016)

(a) the eclipsed conformation of ethane is more stable than staggered conformation even though the eclipsed conformation has torsional strain

(b) the staggered conformation of ethane is more stable than eclipsed conformation, because staggered conformation has no torsional strain

(c) the staggered conformation of ethane is less stable than eclipsed conformation, because staggered conformation has torsional strain

(d) the eclipsed conformation of ethane is more stable than staggered conformation, because eclipsed conformation has no torsional strain.

6. In the following the most stable conformation of n-butane is

(a)                 (b)

(c)                      (d)

7. Liquid hydrocarbons can be converted to a mixture of gaseous hydrocarbons by         (2010)

(a) oxidation

(b) cracking

(c) distillation under reduced pressure

(d) hydrolysis.

8. Which of the following conformers for ethylene glycol is most stable?             (Mains 2010)

(a)                        (b)

(c)                        (d)

15. An alkene on ozonolysis gives methanal as one of the product. Its structure is    (NEET 2020)

(a)                  (b)

(c)                 (d)

16. An alkene A on reaction with O3 and Zn H2O gives propanone and ethanal in equimolar ratio. Addition of HCl to alkene A gives B as the major product. The structure of product B is  (NEET 2019)

(a)              (b)

(c)       (d)